Answer the following questions in about 150 words each : (b) Discuss the sensitive stages for drought and high temperature in cereals and pulses.

Cereals and pulses, vital for global food security, exhibit distinct sensitive stages to drought and high-temperature stresses, which can significantly reduce yield and quality.

Sensitive Stages for Cereals

Cereals like wheat, rice, and maize are particularly vulnerable during their reproductive phases.

• Drought Stress:
  • Tillering and Stem Elongation: Drought during these early vegetative stages can lead to reduced tiller number, stunted growth, and decreased plant height, ultimately affecting the number of spikes per plant and biomass accumulation. (Source: [4], [5])
  • Anthesis (Flowering) and Grain Filling: This is often the most critical period. Drought stress during anthesis can cause pollen sterility, poor fertilization, and reduced kernel numbers. During grain filling, it leads to a shorter grain-filling period, reduced kernel weight, and increased chalkiness in grains like rice. (Source: [1], [2], [4], [9], [23])
• High Temperature Stress:
  • Vegetative Stage (e.g., Rice Tillering): Temperatures exceeding critical thresholds (e.g., 32-37.5°C for rice) can inhibit tiller bud germination and growth, leading to a reduction in tiller numbers. (Source: [8])
  • Anthesis (Flowering): High temperatures are highly detrimental, causing pollen sterility, reduced pollen viability, impaired anther dehiscence, and poor fertilization, leading to significant spikelet sterility and reduced grain setting. (Source: [1], [12], [17], [24])
  • Grain Filling: Heat stress accelerates grain maturation, leading to incomplete filling, reduced grain weight, and deteriorated grain quality (e.g., increased chalkiness in rice). (Source: [1], [3], [10], [14])

Sensitive Stages for Pulses

Pulses such as chickpea and pigeonpea are also highly susceptible, especially during their reproductive development.

• Drought Stress:
  • Flowering and Podding/Pod Filling: These are the most sensitive stages. Drought stress during flowering can cause flower abortion, poor pod set, and reduced number of pods per plant. During pod filling, it can lead to smaller seed size and fewer seeds per pod, significantly impacting final yield. (Source: [1], [2], [18], [28], [34])
  • Early Podding/Vegetative Stages: Some studies indicate that early podding vegetative stages are also critical for water stress in chickpea, affecting overall biomass and yield. (Source: [18])
• High Temperature Stress:
  • Floral Development and Flowering: Pulses are extremely sensitive to high temperatures during floral development and flowering, leading to massive flower drop (e.g., in pigeonpea), pollen sterility, reduced pollen germination, and poor pod formation. (Source: [1], [6], [15], [16], [20], [22])
  • Pod Filling: High temperatures during pod filling can accelerate pod development, lead to embryo abortion, and result in smaller and fewer seeds. (Source: [1], [16], [20])

Comparative Summary of Sensitive Stages

The table below summarizes the critical stages for both cereals and pulses under drought and high-temperature stress:

Stress Type	Crop Type	Most Sensitive Stages	Key Impacts
Drought	Cereals	Tillering, Anthesis (Flowering), Grain Filling	Reduced tillers, pollen sterility, poor fertilization, low kernel number and weight.
	Pulses	Flowering, Pod Formation, Pod Filling	Flower abortion, poor pod set, reduced seed size and number.
High Temperature	Cereals	Anthesis (Flowering), Grain Filling	Pollen sterility, reduced viability, spikelet sterility, accelerated maturation, reduced grain weight and quality.
	Pulses	Floral Development, Flowering, Pod Filling	Flower drop, pollen sterility, poor pod set, embryo abortion, smaller seeds.